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《量子电子学报》2014,(1)
在受激辐射粒子加速(PASER)中,受激介质中处于激发态的电子跃迁到基态时辐射的光子能量直接以量子形式转移给从它旁边经过的电子、首先对单个电子柬团穿过受激介质时产生的电场进行了理论推导,并分别对受激的二氧化碳混合气体和受激氟化氩混合气体进行了计算、计算结果表明加速梯度可以达到1 GV/m,比现有的普通加速器(如盘和波导加速结构)加速梯度高两个数量级。此外,通过二维模型进一步分析了电子微柬团串穿过受激的混合气体介质获得的能量增益。结果表明电子束团串可显著吸收受激介质中的量子态能量,且吸收的能量与相互作用长度成正比、在相互作用长度等于0.5 m时对柬团参数和其它的量对能量交换的影响进行了分析、通过理论计算给出了电子获得最大能量增益时的优化参数、 相似文献
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在受激辐射粒子加速中(PASER), 受激介质中处于激发态的电子跃迁到基态时辐射的光子能量直接以量子形式转移给从它旁边经过的电子。本文首先对单个电子束团穿过受激介质时产生的电场进行了理论推导,并分别对受激的二氧化碳混合气体和受激氟化氩混合气体进行了计算。计算结果表明加速梯度可以达到1GV/m,比现有的普通的加速器加速梯度20~30MV/m高两个数量级。此外,通过二维模型进一步分析了电子微束团串穿过受激的混合气体介质获得的能量增益。结果表明电子束团串可以显著地吸收受激介质中的量子态能量,且吸收的能量与相互作用长度成正比。在相互作用长度等于0.5m时对束团参数和其它的量对能量交换的影响进行了分析。通过理论计算给出了电子获得最大能量增益时的优化参数。 相似文献
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研究了存在非线性Kerr介质时,耦合双原子与单模压缩真空场相互作用系统的Pancharatnam相位特性。选取合适的初始条件和运用旋波近似,通过解薛定谔方程求出Pancharatnam相位的表示形式,并对此相位进行数值分析。结果表明:耦合双原子处于任意初态,随着原子与光场相互作用强度、两个二能级原子偶极-偶极耦合强度和非线性Kerr介质非线性的增大,Pancharatnam相位演化的频率都显著增长。耦合双原子初态同处激发态时,pancharatnam相位演化有明显的振荡上升(或振荡下降)的趋势。耦合双原子初态只有一个处于激发态时,随着Kerr介质非线性作用的增强,Pancharatnam相位演化变混乱。 相似文献
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《量子电子学报》2014,(1)
研究了存在非线性Kerr介质时耦合双原子与单模压缩真空场相互作用系统的Pancharatnam相位特性、选取合适的初始条件并运用旋波近似,通过解薛定谔方程求出Pancharatnam相位的表示形式,并对此相位进行数值分析、结果表明:耦合双原子处于任意初态,随着原子与光场相互作用强度、两个二能级原子偶极-偶极耦合强度和非线性Kerr介质非线性的增大,Pancharatnam相位演化的频率都显著增长、耦合双原子初态同处激发态时,Pancharatnam相位演化有明显的振荡上升(或振荡下降)趋势、耦合双原子初态只有一个处于激发态时,随着Kerr介质非线性作用的增强,Pancharatnam相位演化变混乱、 相似文献
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当强光脉冲和吸收染料相互作用时,染料中将产生大量的激发态分子从而降低了基态吸收。如果光脉冲宽度△t_L比荧光寿命τ_F短而且激发态的吸收可以忽略时,染料激发态的分子数就等于吸收光子数。此时,吸收染料介质可作为光子计数器。皮秒光脉冲能量可由测量光脉冲通过染料样品的能量透射率T_E来决定。用这种办法可校正光电探测器的绝对皮秒脉冲能量,当测量了能量透射率和输入峰值光强时,便可用简单公式计算脉冲宽度,因而这为皮秒 相似文献
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利用全量子理论,讨论了克尔媒质中耦合V型三能级原子与相干态光场相互作用过程中原子信息熵的演化特性。数值计算结果表明,原子信息熵的演化特性对系统初始时刻场平均光子数的大小很敏感。初始时刻场的平均光子数比较大时,原子信息熵的演化会出现明显的周期性崩塌和回复现象。初态中原子激发态概率幅、原子间耦合强度、失谐量与克尔系数等系统... 相似文献
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利用泵浦-探测技术研究高振动激发态KH(V=14-21)分子与CO2的振动-转动碰撞转移过程。脉冲激光激发KH分子至高位振动态,与CO2发生振动-转动能量转移,使CO2高位转动态得到布居,通过测量CO2(0000,J)转动态分布,得到其平均转动能和平均转动能变化,发现振动量子数V从14增加至21时,CO2平均转动能变化增加了2.33倍;测量CO2转动能级的多普勒增宽吸收线,得到V=14和20时,其获得的平均平动能大体随J增大而线性增大;最后,在单一碰撞条件下,测量KH(V=14-21)与CO2(0000,J)的振动-转动碰撞能量转移速率系数,结果显示V=19的总碰撞速率系数是V=14的4.5倍,而V>19则呈下降趋势。 相似文献
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The sudden perturbation method has been used to calculate the excitation cross section of some of the states of Ne II, Ar II, and Kr II by high energy electrons. In this method, the ground state of the noble gas atom, after a collision with a fast electron, is considered to lose one of its valence electrons in a time shorter than the relaxation time of the atom. The resulting configuration is then assumed to be a|(p^{5}) ^{2}P_{j}rangle state withJ = 3/2 or 1/2, with the remaining five valence electrons having the same radial coordinates as in the original|(p^{6})^{1}S_{0}rangle state of the neutral atom. The configuration|(p^{5})^{2}P_{j}rangle is then expanded in terms of the ionic wave functions having the form of|(p^{4})bar{L}bar{S}, nl', LSJrangle , wherebar{L},bar{S} designate the total orbital angular momentum and the total spin angular momentum of the core electrons,l' is the orbital angular momentum of the excited running electron, andLSJ designates the final orbital, spin, and total angular momenta of the atom. The coefficients of the expansion are calculated in terms of the coefficients of fractional parentage and3-j symbols. The radial wave functions for the neutral atoms and their excited ionic states for the involved radial integrals are obtained by using a computer program giving the self-consistent Hartree-Fock wave functions in the Slater approximation. Since no experimental measurements for the excitation cross sections with fast electrons are given, the results of the calculations are indirectly compared with the available work reported on the pulsed Ar II laser. Population of various excited ionic states is calculated assuming a uniform energy distribution of electrons having 1.8 times the ionization threshold of argon, and the results are compared with experimental data reported in the literature. 相似文献
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用量子化学从头计算的单双迭代,包含非迭代三重激发微扰的耦合簇CCSD(T)方法和相关一致基组aug—CC—pV5Z,并采用了3s3p2dlflg基集的高斯键函数,计算THe—AlH复合物体系的相互作用势,构造了刚性转动模型的函数形式。然后用密耦方法计算了He原子低能入射时与基态AlH分子碰撞的分波截面。计算结果表叽总分波截面呈有规律的散射振荡是由强排斥势产生的,在较强的排斥作用区域,才能产生最大的转动激发。。 相似文献
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采用Lee-Low-Pines (LLP)变分法研究了纤锌矿GaN/Al0.3Ga0.7N量子阱中自由极化子能量和电子-声子相互作用对自由极化子能量的影响.理论计算中考虑了量子阱中定域声子模(Confined phonon modes)和半空间声子模(Half-space phonon modes)的影响以及电子有效质... 相似文献
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The technique of polarization-decoupled Brillouin-enhanced four-wave mixing is known for its high-reflectivity, high-quality phase conjugation. The treatment accounts for the transverse structure of the pump and signal beams within a waveguide in the paraxial approximation, assuming a steady-state acoustic wave and assuming that many transverse modes of the waveguide are excited by the four mixing waves. The zeroth-order equations are obtained for the polarization states of the signal and conjugate beams by dropping all phase-mismatch terms. Under the stated assumptions, the phase-mismatched terms are found to make only a small contribution. A first-order solution accounts for phase-mismatch terms and determines the loss of conjugation fidelity as a function of the angular spread of the pump laser beam, the pump-signal angle, the pump intensities, and the pump mutual fidelity 相似文献
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Conventional thermally activated delayed fluorescence (TADF) molecules achieve small energy differences between the lowest singlet and triplet excited states (ΔEST) by enhancing the intramolecular charge transfer, which inevitably leads to a wide emission spectrum and low fluorescence rate. Here, we prepared a deep blue TADF molecule via a small ΔEST pyridine-phenol fluoroboron complex as the acceptor. The small ΔEST is maintained when carbazole donors are attached to the 4-position of the phenyl rings in the fluoroboron complex. Benefiting from the strong electron coupling between the donor (D) and acceptor (A) moieties, the compound Cz-4-BF exhibits a high fluorescence rate of 4.8 × 108 s−1 and a small D-A dihedral angle change in the excited state. Consequently, a photoluminescence (PL) quantum yield of nearly 100% and a PL spectrum with full-width at half-maximum (FWHM) < 60 nm were obtained in solution and low-concentration doped films. A TADF-sensitized fluorescence (TSF) device containing Cz-4-BF achieves an external quantum efficiency of 21%, which is higher than the devices employing classical fluorescent emitters and multiple resonance-type TADF emitters. The Cz-4-BF-based TSF device shows significantly improved color coordinates of (0.14, 0.10) versus a control device without Cz-4-BF. 相似文献
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We use multi-population rate equations model to study feedback oscillations in the quantum dot laser. This model takes into
account all peculiar characteristics in the quantum dots such as inhomogeneous broadening of the gain spectrum, the presence
of the excited states on the quantum dot and the non-confined states due to the presence of wetting layer and the barrier.
The contribution of quantum dot groups, which cannot follow by other models, is simulated. The results obtained from this
model show the feedback oscillations, the periodic oscillations which evolves to chaos at higher injection current of higher
feedback levels. The frequency fluctuation is attributed mainly to wetting layer with a considerable contribution from excited
states. The simulation shows that is must be not using simple rate equation models to express quantum dots working at excited
state transition. 相似文献
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Monirul Hasan Atul Shukla Viqar Ahmad Jan Sobus Fatima Bencheikh Sarah K. M. McGregor Masashi Mamada Chihaya Adachi Shih‐Chun Lo Ebinazar B. Namdas 《Advanced functional materials》2020,30(30)
Recent studies have demonstrated that in thermally activated delayed fluorescence (TADF) materials, efficient reverse intersystem crossing occurs from nonradiative triplet exited states to radiative singlet excited states due to a small singlet–triplet energy gap. This reverse intersystem crossing significantly influences exciton annihilation processes and external quantum efficiency roll‐off in TADF based organic light‐emitting diodes (OLEDs). In this work, a comprehensive exciton quenching model is developed for a TADF system to determine singlet–singlet, singlet–triplet, and triplet–triplet annihilation rate constants. A well‐known TADF molecule, 3‐(9,9‐dimethylacridin‐10(9H)‐yl)‐9H‐xanthen‐9‐one (ACRXTN), is studied under intensity‐dependent optical and electrical pulse excitation. The model shows singlet–singlet annihilation dominates under optically excited decays, whereas singlet–triplet annihilation and triplet–triplet annihilation have strong contribution in electroluminescence decays under electrical pulse excitation. Furthermore, the efficiency roll‐off characteristics of ACRXTN OLEDs at steady state is investigated through simulation. Finally, singlet and triplet diffusion length are calculated from annihilation rate constants. 相似文献